JP4587118B2 - Short arc discharge lamp - Google Patents

Description

  The present invention relates to a short arc discharge lamp, and more particularly to a short arc discharge lamp used for a light source of a projector, a light source for general illumination, and the like.

  Conventionally, a short arc discharge lamp such as a metal halide lamp that is a light source for general illumination or a high-pressure mercury lamp that is a light source for a projector is provided at both ends of an arc tube portion 11 that forms a discharge space T as shown in FIG. The discharge vessel 10 is formed by connecting sealing portions 12 and 12 extending outward, and a conical columnar anode whose outer diameter decreases toward the tip in the arc tube portion 11 of the discharge vessel 10. 55 and the cathode 14 are disposed so as to face each other, and a light emitting material such as a rare gas and mercury is enclosed, and the anode 55 and the cathode 14 are connected to the arc tube portion from the sealing portions 12 and 12 of the discharge vessel 10. 11 is provided at each of the tip end portions of the anode core rod 16 and the cathode core rod 17 extending along the tube axis L1.

In such a short arc discharge lamp, the wall load at the time of lighting, for example 50~250W / cm ^2, in particular, when the discharge lamp is a metal halide lamp 50-100 W / cm ^2, a high pressure mercury lamp In some cases, it is configured to be 100 to 250 W / cm ² . This is because a discharge lamp having a tube wall load of less than 50 W / cm ² has low luminous efficiency and practical light output cannot be obtained, while the tube wall load is larger than 250 W / cm ^2. This is because in the discharge lamp, fogging due to recrystallization of quartz glass forming the discharge vessel may occur at an early stage due to an excessive increase in the temperature of the tube wall of the arc tube portion.

  In recent years, in short arc discharge lamps, in order to achieve high light output, it has been attempted to increase the current supplied to the discharge lamp, but if the supplied current is assumed to be large There is a problem that the temperature of the anode 15 rises excessively and eventually the service life of the discharge lamp is shortened.

  In order to solve such problems, there has been proposed a discharge lamp in which the anode is configured with an electrode body having a large volume, a large heat capacity, and a large surface area for the purpose of dissipating the heat of the anode with high efficiency (for example, Patent Documents). 1).

However, in order to increase the current supplied to increase the output of light in such a discharge lamp, it is necessary to make the volume of the anode considerably large. As the weight increases, the anode core rod supporting the anode may be bent due to the large weight, and the distance between the electrodes may change, making it impossible to obtain an arc of a desired size.
However, if an anode core rod with a large outer diameter is used so that a heavy anode can be reliably supported, sealing may not be performed completely at the sealing portion, and cracks may occur during lighting. There is a problem that the manufacturing yield of the discharge lamp is increased.
JP 2000-294006 A

  The present invention has been made based on the circumstances as described above, and the purpose thereof is to increase the heat of the anode even if the outer diameter of the anode core rod sealed in the sealing portion is small. An object of the present invention is to provide a short arc discharge lamp that is efficiently dissipated to suppress an increase in temperature of the anode, and can be used stably over a long period of time even if high output of light is realized.

The short arc discharge lamp of the present invention comprises a discharge vessel having an arc tube portion and a sealing portion extending outward from both ends of the arc tube portion, and an anode and a cathode are disposed opposite to each other in the arc tube portion. A short arc discharge lamp that is lit under the condition that the proximal end portion of the core rod is supported by the sealing portion and the tube wall load of the arc tube portion is 50 to 250 W / cm ² ,
In the anode, a composite coil body is provided in which a composite wire in which a metal wire is wound around the outer periphery of a metal core wire at a pitch of 100% is wound around the outer periphery of the tip portion of the anode core rod ,
A coil shielding portion is provided at the tip of the anode core rod, and the composite coil body is provided at a portion of the anode core rod on the base end side with respect to the coil shielding portion,
The coil shielding part has an outer diameter that is the same as or larger than the outer diameter of the composite coil body .

  Moreover, in the short arc discharge lamp of this invention, it can be set as the structure by which the front-end | tip of the said anode core rod and the composite coil body by the said composite wire are welded.

  In the short arc discharge lamp of the present invention, it is preferable that the outer diameter of the composite wire is larger than the outer diameter of the anode core rod.

  According to the short arc discharge lamp of the present invention, basically, the anode core rod can be reliably sealed in the sealing portion, and the anode has a large surface area even if it has a small weight and a small heat capacity. The heat dissipation of the anode is performed with high efficiency and the temperature rise of the anode is suppressed, and as a result, even if the current supplied to the electrode is increased to achieve high light output, it is stable over a long period of time. A short arc discharge lamp that can be used can be obtained.

  Hereinafter, the short arc discharge lamp of the present invention will be described in detail with reference to the drawings.

<First Embodiment>
FIG. 1 is an explanatory sectional view showing an example of the configuration of a short arc discharge lamp of the present invention. This short arc discharge lamp (hereinafter, also simply referred to as “discharge lamp”) is a direct current lighting type high-pressure mercury lamp, an elliptical arc tube portion 11 formed of quartz glass, and the arc tube portion 11. A discharge vessel 10 having sealing portions 12 and 12 connected so as to extend outward from both ends of the discharge vessel 10 is provided.

  In the discharge space T partitioned by the arc tube section 11, the cathodes provided respectively at the tips of the cylindrical anode core rod 16 and cathode core rod 17 made of tungsten, for example, on the tube axis L 1 of the discharge vessel 10. 14 and the anode 15 are arranged to face each other in a state of being close to each other.

  The discharge vessel 10 and the sealing parts 12 and 12 are formed by transforming both ends of a quartz glass pipe body, which is a discharge vessel base material, in a molten state. The metal foil 18 made of, for example, molybdenum, which electrically connects the anode core rod 16 and the external lead rod 19 is hermetically embedded, and the cathode core rod 17 and the external lead rod are disposed inside the other sealing portion 12. A metal foil 18 made of molybdenum, for example, which is electrically connected to 19 is embedded in an airtight manner. The cathode 14 is configured by winding a metal wire 13 around the tip of a cathode core rod 17.

  As shown in FIG. 2, the anode 15 is configured by providing a composite coil body 20 in which a composite wire 25 described later is wound at a pitch of 100% on the outer periphery of the tip portion of the anode core rod 16. Yes.

  As shown in FIG. 3, the composite wire 25 is composed of, for example, a metal wire for forming a composite wire made of molybdenum (hereinafter, also simply referred to as “wire”) 21, for example, a metal core wire 22 made of tungsten (hereinafter, referred to as “wire”). Simply called “core wire”), and the pitch is preferably 100%.

  It is preferable that the outer diameter P of the composite wire 25 is equal to or larger than the outer diameter Q of the anode core rod 16.

  Here, the outer diameter P of the composite wire 25 is expressed by the formula: (p1 × 2) + p2 where the outer diameter of the strand 21 is p1 and the outer diameter of the core wire 22 is p2, and in an example of dimensions, p1 Is 0.2 mm, and p2 is 0.3 mm. In this case, P is 0.7 mm.

  The length L of the composite coil body 20 formed by winding the composite wire 25 on the anode core rod 16 varies depending on the outer diameter P of the composite wire 25, but is usually 2 to 5 mm. In a specific example, When the outer diameter P of the composite wire 25 is 0.7 mm, the length L of the composite coil body 20 is 5.0 mm.

The discharge space T of the discharge vessel 10 is filled with mercury as a luminescent substance in an amount of, for example, 0.1 to 0.3 mg / mm ^3, and bromine is, for example, 1.7 × 10 ^{−4 to} 6. It is sealed in an amount of 7 × 10 ⁻⁴ μmol / mm ^3, and a buffer gas made of a rare gas such as argon is sealed at a sealing pressure of, for example, 2.0 atmospheres.

An example of the dimensions of this discharge lamp is as follows.
The arc tube portion 11 has a maximum outer diameter of 9 to 15 mm, a maximum inner diameter of 3 to 9 mm, and a length of the sealing portion 12 of 10 to 20 mm. Moreover, the outer diameter Q of the anode core rod 16 is 0.2-0.7 mm. The distance between the cathode 14 and the anode 15 is, for example, 1.0 to 2.0 mm.
Further, the discharge lamp, the bulb wall loading is 50~250W / cm ² of the arc tube portion 11, so that preferably is lit up with the conditions to be 100 to 200 W / cm ^2, for example, the rated voltage is 80V, the rated current It is configured with 2.0A and rated power of 160W.
If the tube wall load is less than 50 W / cm ² , the luminous efficiency is low and practical light output cannot be obtained. On the other hand, if the tube wall load is greater than 250 W / cm ² , Due to an excessive increase in the temperature of the tube wall, fogging due to recrystallization of the quartz glass forming the discharge vessel 10 may occur at an early stage and the service life may be shortened.

  In the short arc discharge lamp having the above configuration, light is emitted by arc discharge generated between the cathode 14 and the anode 15 by being connected to an appropriate power supply device (not shown) and turned on. The

According to the above discharge lamp, since the anode 15 is configured by providing the composite coil body 20 made of the composite wire 25, the anode core rod 16 is reliably supported by the sealing portion because its weight is small, Even if the heat capacity is small, it has a large surface area, so that heat dissipation of the anode can be realized with high efficiency, and as a result, an increase in temperature of the anode 15 can be suppressed.
As a result, it is possible to obtain a short arc discharge lamp that can be used stably over a long period of time even if the current supplied to the discharge lamp is increased to achieve high light output.

As mentioned above, although embodiment of this invention was described, this invention is not limited to said aspect, A various change can be added.
For example, the short arc discharge lamp of the present invention is not limited to being configured as a high-pressure mercury lamp in which mercury is enclosed as a luminescent material. For example, a metal halide lamp using a mixture of a metal vapor such as mercury and a halogen as a luminescent material. It may be configured as.
In an example of a metal halide lamp, a thin film of metal oxide such as aluminum oxide (Al ₂ O ₃ ) and niobium oxide (Nb ₂ O ₅ ) is formed on the inner surface of the arc tube portion 11 to a thickness of 0.1 μm, for example, by a sol-gel method. In the discharge space T of the discharge vessel 10, for example, 5-20 mg of tin dibromide (SnBr ₂ ) as a metal halide, and xenon gas as a buffer gas, for example, are sealed at a pressure of 5 atm. Further, for example, the rated voltage is set to 80 V, the rated current is set to 3.1 A, and the rated power is set to 250 W so that the arc tube section 11 is turned on under the condition that the tube wall load is 50 to 100 W / cm _2. .

Further, the shape and structure of the discharge vessel are not limited to those shown in FIG. 1, and various configurations can be employed.
Furthermore, the sealing structure in the sealing portion is not limited to a foil seal structure using a metal foil, but may be another structure such as a rod seal structure.

<Second Embodiment>
As shown in FIG. 4, the anode 35 in the short arc discharge lamp of this example has an outer diameter equal to or larger than the outer diameter R of the composite coil body 20 made of the composite wire 25 at the tip of the anode core rod 16. The coil shielding portion 28 is provided, and the composite coil body 20 is provided in a portion of the anode core rod 16 closer to the proximal end than the coil shielding portion 28. The anode 35 has the same configuration as that of the discharge lamp in the first embodiment except that the anode 35 has the above configuration.

Specifically, the coil shielding part 28 is in the shape of a truncated cone column whose outer diameter decreases toward the tip.
The coil shielding part 28 is made of the same material as that constituting the anode core rod 16. In this example, the coil shielding part 28 is made of tungsten, and its maximum outer diameter U is, for example, 1.5 to 2.1 mm, and particularly preferably the same size as the outer diameter R of the composite coil body 20.
The outer diameter R of the composite coil body 20 is represented by the formula: (P × 2) + Q, where P is the outer diameter of the composite wire rod 25 and Q is the outer diameter of the anode core rod 16. For example, in one example, P is 0.7 mm, Q is 0.7 mm, and in this case, R is 2.1 mm.

  According to such a discharge lamp, since the coil shielding part 28 is interposed, the composite coil body 20 is prevented from coming into direct contact with the arc, so that the composite coil body 20 is reliably prevented from being melted. The Thereby, since the change in the distance between the cathode 14 and the anode 35 is small, the arc is maintained at a desired size over a long period of time, and as a result, desired lamp characteristics can be obtained over a long period of time.

<Third Embodiment>
As shown in FIG. 5, the anode 45 in the short arc discharge lamp of this example has a welded portion 29 in which the tip of the anode core rod 16 and the composite coil body 20 made of the composite wire 25 are welded. . The anode 45 has the same configuration as the discharge lamp in the first embodiment except that the anode 45 has the above configuration.

  Specifically, the welded portion 29 is formed by melting a region in contact with the composite coil body 20 in the anode core rod 16 and integrally welding the composite wire body 25 constituting the composite coil body 20. It is a thing.

  According to this discharge lamp, the composite coil body 20 is securely fixed to the tip of the anode core bar 16 in addition to the effect that heat dissipation is performed with high efficiency, similar to the discharge lamp in the first embodiment. Therefore, it is possible to obtain an effect that a stable arc can be obtained regardless of the posture of the discharge lamp.

  Examples of the short arc discharge lamp of the present invention will be specifically described below, but the present invention is not limited to these.

<Example 1>
According to the configuration shown in FIG. 1, a high-pressure mercury lamp having the following specifications was produced.

Discharge vessel (10): material: quartz glass, dimensions: 11 mm overall length of discharge vessel (10), outer diameter of arc tube portion (11) 11.0 mm, inner diameter of arc tube portion (11) 7.0 mm, arc tube The inner volume 140 mm ³ of the part (11), the length of the sealing part (12) 20 mm,
Anode core rod (16): material: tungsten, dimensions: length 10 mm, outer diameter 0.7 mm,
Anode (15): Material: Tungsten, Dimensions: Maximum outer diameter of anode (15) 2.1 mm, Length of anode (15) 5 mm, Metal strand (21) is tungsten, Metal strand (21) The outer diameter of the core wire (22) is tungsten, the outer diameter of the core wire (22) is 0.3 mm, the winding pitch of the composite wire (25) around the anode core rod (16) is 100%,
-Cathode (14): Material: Tungsten, Dimensions: Length of cathode core rod (17) 10 mm, outer diameter of cathode core rod (17) 0.7 mm,
The distance between the cathode (14) and the anode (15): 1.2 mm,
Lighting conditions: Rated current: 2 A, rated voltage: 80 V, rated power: 160 W, tube wall load: 100 W / cm ² ,
-Inclusion material: Argon gas (pressure at the time of encapsulation 0.2 atmospheres), mercury 20 mg, bromine 80 μg

The high-pressure mercury lamp was turned on, and the temperature of the anode at the time of stable lighting was measured by a method in which the infrared radiation intensity from a predetermined position of the anode was measured and compared with a temperature calibrated in advance. The results are shown in Table 1.
However, in this high pressure mercury lamp, the anode refers to the tip portion of the composite coil body (20) and the anode core rod (16) on which it is disposed.

<Example 2>
Except that the anode core rod has an outer diameter of 0.4 mm and the composite coil body (20) and the anode composed of the tip portion of the anode core rod (16) around which the composite coil body (20) is to be wound are configured in the same manner as in Example 1. Then, a high-pressure mercury lamp was manufactured and lit, and the anode temperature was measured in the same manner as in Example 1. The results are shown in Table 1.

<Comparative Example 1>
Example 1 except that an anode provided with a coil formed by winding a tungsten wire having an outer diameter of 0.7 mm around an anode core rod (16) instead of the composite wire (25) was used. In the same manner as described above, a high pressure mercury lamp was produced and lit, and the temperature of the anode was measured in the same manner as in Example 1. The results are shown in Table 1.
However, in this high-pressure mercury lamp, the anode refers to the tip of the coil and the anode core rod (16) on which the coil is disposed.

<Control Example 1>
High pressure mercury as in Example 2 except that an electrode body having the same shape as the anode shown in FIG. 6 having a frustum shape having an outer diameter of 1.8 mm and a length of 5 mm was provided as the anode at the tip of the anode core rod. A lamp was produced and lit, and the anode temperature was measured in the same manner as in Example 1. The results are shown in Table 1.

  In Table 1, the weight ratio of the anode is a numerical value when the weight of the truncated conical columnar electrode body (control example 1) having the maximum outer diameter of the anode of 1.8 mm and the length of the anode of 5 mm is 1. The numerical values shown in the columns of radiation, convection, and heat conduction in the ratio of heat flow from the anode are calculated from the surface area of the anode.

  According to the above results, it was confirmed that the high-pressure mercury lamp according to Example 1 can lower the temperature of the anode as compared with Comparative Example 1 including an anode having an equivalent outer diameter. Moreover, in the high pressure mercury lamp which concerns on Example 2, it was confirmed that the temperature of an anode can be made lower than the thing which concerns on the comparative example 1 in spite of a small outer diameter.

<Example 3>
A metal halide lamp according to the following specifications was manufactured according to the configuration shown in FIG.

Discharge vessel (10): material: quartz glass, dimensions: 12 mm overall length of discharge vessel (10), outer diameter of arc tube portion (11) 13.0 mm, inner diameter of arc tube portion (11) 8.0 mm, arc tube The inner volume of the part (11) is 270 mm ³ , and an oxide film having a thickness of 0.1 μm made of aluminum oxide (Al ₂ O ₃ ) is formed on the inner surface of the arc tube part (11) by a sol-gel method.
Anode core rod (16): material: tungsten, dimensions: length 11 mm, outer diameter 0.7 mm,
-Anode (15): Material: Tungsten, Dimensions: Maximum outer diameter of anode (15) 2.1mm, Length of anode (15) 5mm, Metal strand (21) is molybdenum, Metal strand (21) The outer diameter of the core wire (22) is tungsten, the outer diameter of the core wire (22) is 0.3 mm, the winding pitch of the composite wire (25) around the anode core rod (16) is 100%,
-Cathode (14): Material: Tungsten, Dimensions: Length of cathode core rod (17) 11 mm, outer diameter of cathode core rod (17) 0.7 mm,
The distance between the cathode (14) and the anode (15): 1.5 mm,
Lighting conditions: Rated current; 3.1 A, rated voltage; 80 V, rated power; 250 W, tube wall load; 125 W / cm ² ,
-Inclusion material: Xenon gas (pressure at the time of encapsulation 5.0 atm), tin dibromide (SnBr ₂ ) 20 mg, bromine 80 μg

The metal halide lamp thus produced was turned on, and the anode temperature during stable lighting was measured by the same method as in Example 1. The results are shown in Table 2.
However, in this metal halide lamp, the anode refers to the tip portion of the composite coil body (20) and the anode core rod (16) on which it is disposed.

<Example 4>
Except that the outer diameter of the anode core rod was 0.6 mm, and the anode composed of the tip portion of the composite core body (20) and the anode core rod (16) around which the composite coil body (20) was wound was configured. A metal halide lamp was produced and lit, and the anode temperature was measured in the same manner as in Example 1. The results are shown in Table 2.

<Comparative example 2>
Example 3 except that an anode provided with a coil formed by winding a wire made of tungsten having an outer diameter of 0.7 mm around an anode core rod (16) instead of the composite wire (25) was used. In the same manner as described above, a metal halide lamp was produced and lit, and the temperature of the anode was measured in the same manner as in Example 1. The results are shown in Table 2.
However, in this high-pressure mercury lamp, the anode refers to the tip of the coil and the anode core rod (16) on which the coil is disposed.

<Control Example 2>
A metal halide lamp was produced in the same manner as in Example 4 except that an electrode body having the same shape as the anode shown in FIG. 6 having a frustum shape having an outer diameter of 1.8 mm and a length of 5 mm was provided as the anode at the tip of the anode core rod. Was made to light, and the temperature of the anode was measured by the same method as in Example 1. The results are shown in Table 2.

  In Table 2, the weight ratio of the anode is a numerical value when the weight of the truncated conical columnar electrode body (control example 2) in which the maximum outer diameter of the anode is 1.8 mm and the length of the anode is 5 mm is 1. The numerical values shown in the columns of radiation, convection, and heat conduction in the ratio of heat flow from the anode are calculated from the surface area of the anode.

  According to the above results, it was confirmed that the metal halide lamp according to Example 3 can lower the temperature of the anode as compared with Comparative Example 2 including the anode having the same outer diameter. Moreover, in the metal halide lamp which concerns on Example 4, it was confirmed that the temperature of an anode can be made lower than the thing which concerns on the comparative example 2 although an outer diameter is small.

It is sectional drawing for description which shows an example of a structure of the short arc discharge lamp of this invention. It is explanatory drawing which expands and shows typically the anode of the short arc discharge lamp of FIG. It is explanatory drawing which shows typically the structure of a composite wire in the state which made the part the cross section. It is explanatory drawing which shows typically the other example of a structure of the anode of the short arc discharge lamp of this invention. It is explanatory drawing which shows typically the further another example of a structure of the anode of the short arc discharge lamp of this invention. It is sectional drawing for description which shows an example of a structure of the conventional short arc discharge lamp.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Discharge container T Discharge space 11 Light emission tube part 12 Sealing part 13 Metal wire 14 Cathode 15 Anode 16 Anode core rod 17 Cathode core rod 18 Metal foil 19 External lead rod 20 Composite coil body 21 Metal element wire 22 Metal core wire 25 Composite wire material 28 Coil shielding part 29 Welding part 35, 45, 55 Anode L1 Tube axis

Claims (3)

A discharge vessel having an arc tube portion and a sealing portion extending outward from both ends of the arc tube portion, the anode and the cathode are disposed oppositely in the arc tube portion, and the base end portion of the anode core rod is sealed A short arc discharge lamp that is supported by the light source and is lit under the condition that the tube wall load of the arc tube is 50 to 250 W / cm ² ,
In the anode, a composite coil body is provided in which a composite wire in which a metal wire is wound around the outer periphery of a metal core wire at a pitch of 100% is wound around the outer periphery of the tip portion of the anode core rod ,
A coil shielding portion is provided at the tip of the anode core rod, and the composite coil body is provided at a portion of the anode core rod on the base end side with respect to the coil shielding portion,
The short arc discharge lamp according to claim 1, wherein the coil shielding portion has an outer diameter equal to or larger than an outer diameter of the composite coil body . The short arc discharge lamp according to claim 1, wherein a tip of the anode core rod and a composite coil body made of the composite wire are welded . The short arc discharge lamp according to claim 1 or 2 , wherein an outer diameter of the composite wire is greater than or equal to an outer diameter of the anode core rod .

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